Scientists have grown stem cells from adults using cloning techniques for the first time, bringing them closer to developing patient-specific lines of cells that can be used to treat a host of ailments, from heart disease to blindness.
The research, described in Thursday's online edition of the journal Cell Stem Cell, is a controversial advance likely to reopen the debate over the ethics of human cloning.
The scientists' technique was similar to the one used in the first clone of a mammal, Dolly the sheep, which was created in 1996.
They "reprogrammed" an egg cell by removing its DNA and replacing it with that of an adult donor. Scientists then zapped the cell with electricity, which made it divide and multiply. The resulting cells were identical in DNA to the donor.
The first success in humans was reported last year by scientists at the Oregon Health & Science University and the Oregon National Primate Research Center. But they used donor cells from infants. In this study, the cells came from two men, a 35-year-old and a 75-year-old.
Paul Knoepfler, an associate professor at the University of California at Davis who studies stem cells, called the new research "exciting, important, and technically convincing."
"In theory you could use those stem cells to produce almost any kind of cell and give it back to a person as a therapy," he said.
In their paper, Young Gie Chung, from the Research Institute for Stem Cell Research for CHA Health Systems in Los Angeles; Robert Lanza, from Advanced Cell Technology in Marlborough, Mass.; and their co-authors emphasized the promise of the technology for new therapies. What they didn't mention, but was clear to those working with stem cells, was that their work was also an important discovery for human cloning.
While the research published Thursday involves cells that are technically early stage embryos, the intention is not to try to grow them into a fully formed human. However the techniques, in theory, could be a first step toward creating a baby with the same genetic makeup as a donor.